Hydrogen storage alloy, hydrogen separation membrane, hydrogen storage tank, and hydrogen absorption and desorption method

A hydrogen separation membrane which selectively separates hydrogen from a hydrogen-containing gas, the membrane containing a hydrogen storage alloy including a composition defined by the following formula:

• (Ca1-XLX)(Li1-Y-ZMYNiZ)m
• wherein the L denotes one or more elements selected from the group consisting of Na, K, Rb, Cs, Mg, Sr, Ba, Sc, Ti, Zr, Hf, V, Nb, Ta, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu;
• the M denotes one or more elements selected from the group consisting of Cr, Mo, W, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and S;
• and the mole ratios X, Y, Z, and m respectively satisfy the following:
• 0<X≦0.4, 0≦Y≦0.4, 0.1≦Z≦0.4, and 1.8≦m≦2.2.

A hydrogen storage tank comprising:

• a pressure vessel having a hydrogen gas lead-in port;
• and
• a hydrogen storage alloy contained in the pressure vessel and including a composition defined by the following formula:
• (Ca1-XLX)(Li1-Y-ZMYNiZ)m
• wherein the L denotes one or more elements selected from the group consisting of Na, K, Rb, Cs, Mg, Sr, Ba, Sc, Ti, Zr, Hf, V, Nb, Ta, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu;
• the M denotes one or more elements selected from the group consisting of Cr, Mo, W, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and S;
• and the mole ratios X, Y, Z, and m respectively satisfy the following:
• 0<X≦0.4, 0≦Y≦0.4, 0.1≦Z≦0.4, and 1.8≦m≦2.2.

A hydrogen absorption and desorption method comprising:

• storing a hydrogen storage alloy powder in the inside of a pressure vessel having a hydrogen gas lead-in port;
• introducing hydrogen gas or hydrogen-containing gas at a predetermined pressure and temperature into the pressure vessel through the lead-in port to absorb the hydrogen gas or hydrogen-containing gas in the hydrogen storage alloy;
• and
• desorbing hydrogen from the hydrogen storage alloy under predetermined pressure and temperature conditions,
• the hydrogen storage alloy including a composition defined by the following formula:
• (Ca1-XLX)(Li1-Y-ZMYNiZ)m
• wherein the L denotes one or more elements selected from the group consisting of Na, K, Rb, Cs, Mg, Sr, Ba, Sc, Ti, Zr, Hf, V, Nb, Ta, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu;
• the M denotes one or more elements selected from the group consisting of Cr, Mo, W, Mn, Fe, Ru, Co, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and S;
• and the mole ratios X, Y, Z, and m respectively satisfy the following:
• 0<X≦0.4, 0≦Y≦0.4, 0.1≦Z≦0.4, and 1.8≦m≦2.2.